This is adapted from the Sante Fe Woman's Club cookbook - it's a high altitude recipe, but if you aren't at a high altitude, you can tweak the ingredients. (As a rough guess, cut back on the flour and watch it carefully while baking since it may cook faster. It won't rise as much.)
You'll need a muffin tin. The one we use is one of those giant muffin tins with the wider holes. Custard molds would work nicely as well. You want these to be oven safe.
Heat the oven to 450 and butter and flour (or use cocoa to not have the pale marks) the tin. A single batch makes 3 lovely cakelets, so butter accordingly.
In a small saucepan or double boiler, heat a stick of butter and 4 oz. (4 squares) of chocolate. If you use bittersweet chocolate two packets of Splenda, the recipe is safe for a low sugar diet. When the chocolate is almost completely melted take the pan off the heat.
Note : The first few times I've tried this, it was dry. So last time, we added about two tablespoons of sour cream mixed with about a quarter teaspoon of vanilla. The flour (two teaspoons) was mixed in the sour cream for convienence. Almond seasoning, cinnamon, rose water etc. would be interesting in moderation.
While the chocolate and butter are heating, beat two eggs and two egg yolks with 1/4 cup of sugar or two packets of Splenda until light and thick. It should look a sort of buttery yellow. Mix the butter and chocolate together (since it's all separated in the pan if you didn't touch it while heating) and then pour it (still warm) into the egg mixture. If you are using sour cream, mix it in. If not, beat in two teaspoons of flour.
Plop the stuff in the greased and floured tins and pop in the oven. Check the stuff after 10 minutes. The sides should be set, and the middle soft. Turn the muffin tin upside down over a plate or other flat surface. Count to ten, and then lift the tin carefully. The cakelets should fall out.
Serve immediately. The texture is soft and moist, and the chocolate flavor is lovely. If they cool, they're still edible tough.